Conventionally, there has been known an internal combustion engine equipped with an EGR (Exhaust Gas Recirculation) system for circulating exhaust gas after combustion to an intake air passage as disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2009-74459.
The internal combustion engine disclosed in the aforementioned Publication is provided with a supercharger and two EGR paths. A first path is a path for circulating exhaust gas after combustion from the upstream side of a turbine of a supercharger to the downstream side of a compressor thereof. The EGR system having such an EGR path is also called HPL(High Pressure Loop)-EGR system. A second path is a path for circulating exhaust gas after combustion from the downstream side of the turbine of the supercharger to the upstream side of the compressor thereof. The EGR system having such an EGR path is also called LPL(Low Pressure Loop)-EGR system.